Telecommunication switching systems



Sept. 23, 1909 Filed March 28, 1966 C. F. J. HILLEN TBLECOMMUNICATION SWITCHING SYSTEMS 4 Sheets-Sheet 2 i Mwl 2A7 3A 1 4A7 SA? 202 302 402 552 203 353 403 503 204 304 404 504 255 305 405 505 SWITCH 07 201 301 407 501 202 .302 402 5A2 203 3A3 403 553 204 304 4A4 504 245 305 405 505 W I t l 201 301 401 501 202 352 4A2 502 253 303 403 5A3 2A4 304 404 4 205 3A5 4E5 505 w 201 307 401 501 202 3A2 402 502 243 303 403 503 204 3E4 404 5A4 205 305 4A5 5E5 2E7 3E7 45! 5E! 2A2 302 402 502 203 303 443 503 204 3A4 404 504 205 305 405 5A5 lNvENroR BY ([01 fffl/LLE/V,

ATTCRNEY Sept. 23, 1969 c. F. J. HILLEN 3,469,035

TELECOMMUNICATION SWITCHING SYSTEMS 7 Filed March 28, 1956 4 Sheets-Sheet 4 INTERCONNECT/0N5 OF FIRST GROUP OF TERMINALS SWITCH A! 7A7 2A7 3A1 4A7 5A7 I05 265 3B5 4A5 5E5 SWITCH/ll 7A7 2A1 3A1 4A1 SA] IE5 205 365 4B5 5A5 INVEN'TQR (fa/z KIA 445i BY A'TTOQNEY 3,469,035 TELECOMMUNICATION SWITCHING SYSTEMS Cecii Frederick .lohn Hillen, Applecroft, Rectory Drive,

Bidborongh, Kent, England Filed Mar. 23, 1966, Ser. No. 537,838 Claims priority, application Great Britain, Mar. 29, 1965, 13,223/ 65 Int. Cl. Hildrn 3/42 U5. Cl. 179-48 5 Claims ABSTRACT OF THE DISCLOSURE A telecommunication switching stage in which a number of switches arranged in a block as a matrix of rows and columns have their input terminals connected to subscribers lines and their output terminals to the inputs of other switching stages. The inputs are shared by the output terminals of the switches which are interconnected with the inputs by joining each input to an output terminal of a different combination of the switches.

BACKGROUND OF THE INVENTION This invention relates to telecommunication switching systems and in particular to systems employing switches each having a number of inputs and outputs. Each output of each switch is interconnected with an output of one or more other switches, the switches being arranged in a matrix of rows and columns. The term matrix of rows and columns is used herein only as a means of identifying the respective switches which are not necessarily disposed in this manner in a practical layout.

With some existing telephone systems for example, each subscribers line is connected to a line switch giving access via a group of outlets to other selectors, the outlets being shared by a number of subscribers greater in number than the number of outlets in the group, according to specified traffic requirements. The subscribers sharing the outlets are so arranged as to assure as far as possible that all groups of outlets are equally loaded, i.e. where subscribers are known to originate large volumes of traflic they do not share the same outlets leaving other outlets to be shared by subscribers generating less trafiic. This entails constant checks on trai'fic loading and the moving of subscribers from one group of outlets to another.

The object of the invention is to reduce the possibility of blocking, i.e. the condition when all the outputs of a particular switch are engaged, and to permit incoming circuits to be connected at random to the inputs of any switch, without the need to consider the amount of traffic originated by the incoming circuits.

SUMMARY OF THE INVENTION According to the present invention a telecommunication switching system comprises a first group of terminals, a second group of terminals whose number is greater than that of the terminals in the first group, and a plurality of switches each having a first set of terminals connectible by the switch to a second set of switch terminals, the numbers of terminals in the first and second sets being the same for all switches and the terminals of the first set of terminals of each switch being numbered sequentially, the switches being arranged schematically in a matrix of rows and columns, the number of columns being equal to the number of terminals of the first set of terminals of a switch, each terminal of the second set of terminals of the switches being connected to a different one of the terminals of the second group of terminals while each numbered terminal of the first set of terminals of each switch in one row and column is connected to a different terminal of the first group of terminals and to the corre- I; nite States Patent O spondingly numbered terminal of the first set of terminals of a switch in a different row and in a column (xp) relative to the one column, x being the number of the terminal of the first set of terminals of the switch in the one row and column, and p being an integer of value from O to N where N is the number of columns.

Conveniently, the matrix consists of equal numbers of columns and rows and in this specification such a matrix is referred to as a block. A switching system may comprise a number of such blocks each of which may have its own unique first and second groups of terminals, or the corresponding terminals of the first group of terminals of the blocks may be commoned. Again, the system may comprise one or more blocks having their own unique first and second groups of terminals and other blocks of which corresponding first terminals of the first group of terminals are commoned. Within each block the same method of interconnecting the terminals of the first group with the terminals of the first set of terminals of the switches is used, but diiferent methods may be used for dilierent blocks although the use of a common method clearly facilitates the wiring-up of the terminals of the first group and terminals of the switch first sets of terminals.

A block may be enlarged by the addition of one or more switches.

Interconnection of the terminals of the first set of terminals of each switch in a block is arranged so that each terminal of the first group of terminals of the block is connected to a terminal of the first set of terminals of at least one switch in each row.

In a preferred embodiment of the invention, the number of rows and columns is a prime number. In such an embodiment, the interconnection method of a particular terminal of the first group of terminals will involve, in each row, a switch in a different column except for the terminal x=p of the first set of terminals of a switch. Alternatively, if the number of rows and columns is not prime, the interconnection method for some of the terminals of the first group of terminals of a given block will involve the use of more than one switch in some columns other than for the terminal x=p of the first set of terminals of a switch.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block schematic of a first embodiment, and, FIGS. 2, 3, 4, 5 and 6 are explanatory tables of connections.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a block schematic of a first embodiment and shows switches A1 A5, B1 B5, C1 C5, D1 D5 and E1 E5 each switch having a first set of terminals and a second set of terminals equal in number. Each switch may be a crossbar switch, uniselector switches, a co-ordinate array of crosspoint switches or any other suitable form of switch enabling a number of terminals of the first set to be connected to an equal number of terminals of the second set.

In the embodiment of FIG. 1, each switch is in the form of a co-ordinate array of cross-points having 5 terminals in the first and second sets of terminals, the switches being arranged in a matrix, having 5 switches per row and 5 rows per block, making a total of 25 switches per block. Thus, the first column comprises switches A1 AS, the second B1 E5, the third C1 .C5, the fourth D1 D5 and the fifth E1 E5. The first set of terminals of a switch are designated 1A1 5A1, 1B1 5B1 and so on. The block has a second group of terminals 1 and a first group of terminals 1 25. These 25 first terminals are divided into 5 groups, i.e. 5

for each switch in the top row, and in accordance with the interconnection arrangement, each of these terminals of the first group is available to a, different combination of 25 terminals out of the 125 terminals of the first group of terminals.

In FIG. 1 only the interconnection for the terminals 1A1 A1 from the A1 switch and the terminal 1B1 of the B1 switch are shown.

The interconnections shown are of a standardised pattern such that if x designates the number of a switch terminal in the first set it will be connected to the corresponding terminal x of a switch in the next row in a direction away from the terminal in the first set and in a column (x p) in advance which is defined as the direction A1 B1 C1 D1 -E1 A1 B1 p is afactor called the advance factor and has a value of from O to N where N is the number of columns. The embodiment of FIG. 1 uses an advance factor p of 1, connections being made to switches in the next lower row in each case. In FIG. 1, the first group of terminals is at the top of the matrix and connections are made to the terminals of the first sets of terminals of switches in successive rows moving downwardly. If the first group of terminals was shown at the bottom of the matrix, connections would be made to the first set of terminals of switches in successive rows moving upwardly.

Thus, for switch A1, when x, the number of the switch terminal of the first set of switch terminals is 1, (x p) 1 1 0, i.e. no advance, and the terminal 1A1 of switch A1 is connected to the terminal 1A2 of switch A2.

When x is 2, x p 2 1 1 so that the terminal 2A1 of the switch A1 is joined to terminal 2B2 of switch B2, i.e. an advance of one.

When x is 3, x p 3 l 2, so that the terminal 3A1 of switch A1 is joined to the terminal 3C2 of switch C2, i.e. an advance of two.

Whenxis4,xp=4 1 3, sothattheterminal 4A1 of switch Al is joined to the terminal 4D2 of switch D2, i.e. an advance of three.

When x is 5, xp=51=4, so that terminal 5A1 of switch A1 is joined to the terminal 5E2 of switch E2, i.e. an advance of four.

The connections of the other switches follow in like manner. The interconnections are set out in FIG. 2 which lists in columns the interconnected switch first terminals.

The block shown in FIG. 1 can be enlarged to accommodate extra second group terminals by adding further switches. The extra switches have their first sets of terminals connected to the first sets of terminals of the block by repeating the interconnection method of the block. FIG. 1 shows a further row of switches A6 .E6 but only the connections to first terminals 1 5 of switch A6.

The terminal 1A6 of an extra switch A6 schematically disposed beneath switch A5 is joined to terminal 1A5 of switch A5, terminal 2A6 is joined to terminal 2E5 of switch E5, terminal 3A6 is joined to terminal 3D5 of switch D5, terminal 4A6 is joined to terminal 4C5 of switch C5, and terminal 5A6 is joined to terminal 5B5 of switch B5. Further rows of switches could be added, interconnection then simply repeating the pattern of switches A1 E5.

Further self-contained blocks of switches could be added to that shown in FIG. 1 to enlarge the capacity of the switching system. Thus, the addition of another block similar to that shown in FIG. 1 would add a further first group of 25 terminals and another second group of 125 terminals. In the matrix shown in FIG. 1, connections are made from the terminals of the first set of terminals of the switches in one row to those of the switches in the next adjacent row which, in FIG. 1, is the next lower row.

In an alternative embodiment switches each comprising a co-ordinate array of 7 x 7 terminals are used. Using a designation the same as that used above for the 5 x 5 switches, FIG. 3 shows the interconnections for the terminals of the first set of terminals of the A1 switch. The first set of terminals of other switches are interconnected in like fashion.

FIG. 4 shows similar interconnections for 9 x 9 switches.

In FIGS. 3 and 4 an advance factor of 1 is used.

It should be understood that the advancement from column to column may take place as just described when p=1 to the right, from A through B, C, D to E, or alternatively it may be made to the left, from A through E, D, C to B, although for the sake of clarity the first is preferred.

When p equals any other number but 1, it must be decided that advancement in one direction shall be termed positive and in the other direction negative, and although it does not matter which is used, for the sake of clarity, positive to the right and negative to the left is preferable.

For example, consider switch A1 of FIG. 1 and an advance factor p=2, then When x is 1, xp=12=--1 so that terminal 1A1 is joined to terminal 1E2 of switch E2,

When x is 2, x-p=22=0 so that terminal 2A1 is joined to terminal 2A2 of switch A2,

When x is 3, xp:3-2=1 so that terminal 3A1 is joined to terminal 3B2 of switch B2.

Again, consider switch A1 of FIG. 1 and an advance factor p of value 5, then When x is l, x--p=15=4 so that terminal 1A1 is joined to terminal 1B2 of switch B2,

When x is 2, xp=2-5=-3 so that terminal 2A1 is joined to terminal 2C2 of switch C2,

When x is 3, x-p=3-5= 2 so that terminal 3A1 is joined to terminal 3D2 of switch D2,

When x is 4, xp=45=--1 so that terminal 4A1 is joined to terminal 4E2 of switch E2,

When x is 5, x-p=55=0 so that terminal 5A1 is joined to terminal 5A2 of switch A2.

Again, for switch A1 of FIG. 1 and an advance factor p of value 3, then When x is 1, xp=13=--2 so that terminal 1A1 is joined to terminal 1D2 of switch D2,

When x is 2, xp=2-3=1 so that terminal 2A2 is joined to terminal 2E2 of switch E2,

When x is 3, xp=33=0 so that terminal 3A1 is joined to terminal 3A2 of switch A2,

When x is 4, x-p=43=1 so that terminal 4A1 is joined to terminal 4B2 of switch B2,

When x is 5, xp=53=2 so that terminal 5A1 is joined to terminal 5C2 of switch C2.

FIG. 5- shows the interconnections of the terminals of the first set of terminals of switch A1 of FIG. 1 using an advance factor of 4. FIG. 6 shows similar interconnections using an advance factor of 5.

The decision as regards the values of p and the positive and negative directions of advancement must be maintained throughout a block but can be different for other blocks.

It will be appreciated that, in any one block, in the embodiments described above, the interconnection of the terminals of the first set of terminals of switches B1, C1, D1 and E1 is similar to that of the terminals of the first set of terminals of switch A1 and that the interconnections between switches in adjacent rows is likewise similar. Thus, the interconnections take on a standard pattern and, in practice, a standard preformed connection field would be used.

A switching system embodying the invention is suitable for use as a switching stage in an automatic telephone exchange and may be so connected that the second group of terminals are connected to subscribers and the first group of terminals are joined to other switching stages. The system might also be used as the final selector in an automatic telephone exchange in which case the first group of terminals might be junctions from a preceding switching stage and the second group of terminals might be outgoing to subscriber lines.

In a single block, the trafiic from one switch cannot busy all the terminals available to other switches in the same column as the one switch. Further, it will be apparent that the security of the system is relatively high because faults in a block of switches can occur whilst maintaining a minimum grade of service to all or the majority of terminals connected to the block.

The control equipment to be used with the switching system embodying the invention can take any one of the well-known forms and for this reason will not be described in this specification.

I claim:

1. A telecommunication switching system comprising in combination a first group of terminals, a second group of terminals whose number is greater than that of the terminals in the first group, and a plurality of switches each having a first set of terminals connectible by the switch to a second set of switch terminals, the numbers of terminals in the first and second sets being the same for all switches and the terminals of the first set of terminals of each switch being numbered sequentially, the switches being arranged schematically in a matrix of rows and columns, the number of columns being equal to the number of terminals of the first set of terminals of a switch, each terminal of the second set of terminals of the switches being connected to a difierent one of the terminals of the second group of terminals while each numbered terminal of the first set of terminals of each switch in one row and column is connected to a different terminal of the first group of terminals and to the correspondingly numbered terminal of the first set of terminals of a switch in a different row and in a column (x-p) relative to the one column, x being the number of the terminal of the first set of terminals of the switch in the one row and column, and 12 being an integer of value from 0 to N where N is the number of columns.

2. A system as claimed in claim 1 in which each column contains the same number of switches, that number being a prime number.

3. A system as claimed in claim 1 in which each row and each column contain the same number of switches, that number being a number which is not a prime number, and in which each numbered terminal of the first set of terminals of a switch is connected to the correspondingly numbered terminal of a switch in each row.

4. A telecommunication switching arrangement having first and second switching systems as claimed in claim 1 and in which each terminal of the first group of terminals of the first system is connected to one terminal of the first set of terminals of each switch of a different combination of switches of the second system.

5. An arrangement as claimed in claim 4 in which the method of interconnecting the numbered terminals of the first set of terminals of the switches of the second system is identical with that of interconnecting the numbered terminals of the first set of terminals of the first system.

References Cited UNITED STATES PATENTS 2,945,211 7/1960 Gibson et a1 340-147 FOREIGN PATENTS 946,673 1/ 1964 Great Britain.

WILLIAM C. COOPER, Primary Examiner 

